Cis GCP Cos 6.2.8

6.2.8 Ensure users' home directories permissions are 750 or more restrictive (Automated)

Description

While the system administrator can establish secure permissions for users' home directories, the users can easily override these.

Rationale

Group or world-writable user home directories may enable malicious users to steal or modify other users' data or to gain another user's system privileges.

Audit Procedure

Run the following script and verify no results are returned:

#!/bin/bash
grep -E -v '^(halt|sync|shutdown)' /etc/passwd | awk -F: '($7 != "'"$(which nologin)"'" && $7 != "/bin/false") { print $1 " " $6 }' | while read user dir; do
  if [ ! -d "$dir" ]; then
    echo "The home directory ($dir) of user $user does not exist."
  else
    dirperm=$(ls -ld $dir | cut -f1 -d" ")
    if [ $(echo $dirperm | cut -c6) != "-" ]; then
      echo "Group Write permission set on the home directory ($dir) of user $user"
    fi
    if [ $(echo $dirperm | cut -c8) != "-" ]; then
      echo "Other Read permission set on the home directory ($dir) of user $user"
    fi
    if [ $(echo $dirperm | cut -c9) != "-" ]; then
      echo "Other Write permission set on the home directory ($dir) of user $user"
    fi
    if [ $(echo $dirperm | cut -c10) != "-" ]; then
      echo "Other Execute permission set on the home directory ($dir) of user $user"
    fi
  fi
done

Expected Result

No results should be returned.

Remediation

Making global modifications to user home directories without alerting the user community can result in unexpected outages and unhappy users. Therefore, it is recommended that a monitoring policy be established to report user file permissions and determine the action to be taken in accordance with site policy.

Additional Information

On some distributions the /sbin/nologin should be replaced with /usr/sbin/nologin.

CIS Controls

Profile

• Level 2 - Server